Writing instrument



FIG. 1 is a front view of the writing instrument of the present application;

FIG. 2 is a back view of the writing instrument;

FIG. 3 is a side view taken from the left side of the writing instrument;

FIG. 4 is a side view taken from the right side of the writing instrument; and,

FIG. 5 is a top view of the writing instrument. 

The ornamental design for a writing instrument, as shown. 